Fixes for the match grammar #262
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brauliobz
commented
Mar 10, 2018
brauliobz
commented
- added MatchArms to make things clearer
- added attributes to both the match block and match arms
- removed pipes before the patterns, since they're experimental
- added MatchArms to make things clearer - added attributes to both the match block and match arms - removes pipes before the patterns, since they're experimental
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Pipes before the patterns are being stabilized in 1.25. |
Are they really? Where can I follow that? Here: https://github.com/rust-lang/rust/milestone/44 ? I would prefer to only consider things stable when the stable build is published. |
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rust-lang/rust#47947 I added the pipes as a prerequisite for the stabilization, so please keep them. |
Ok, that makes all sense 👍 . |
| > _MatchArm_ `=>` ( [_BlockExpression_] | [_Expression_] ) `,`<sup>?</sup> | ||
| > | ||
| > _MatchArm_ : | ||
| > [_OuterAttribute_]<sup>\*</sup> _MatchArmPatterns_ _MatchArmGuard_ |
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Can you give an example of the OuterAttribute here?
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I can't think of a useful example...
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I tried something like this, but the attribute doesn't apply to the use of deprecated USBType::A and rustc warns about both things instead (unused attribute and use of deprecated item):
enum USBType {
#[deprecated] A,
B,
C,
}
fn describe(ty: USBType) -> &'static str {
use USBType::*;
match ty {
#[allow(deprecated)] A => "",
B => "",
C => ""
}
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So it's allowed by the grammar, but doesn't seem to have a use case? Weird, but as long as it's legal...
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💟 Thanks! |
